class Solution 
{
public:
    vector<vector<int>> subsets(vector<int>& nums)
    {
        vector<vector<int>> ret;
        int n = nums.size();

        for(int st = 0; st < (1 << n); st++)
        {
            vector<int> tmp;
            for(int i = 0; i < n; i++)
            {
                if((st >> i) & 1)
                    tmp.push_back(nums[i]);
            }
            ret.push_back(tmp);
        }
        return ret;
    }
};
